This invention relates to arrangements for restricting outgoing calls from rotary dial station sets and in particular to an arrangement for using an ordinary rotary dial telephone in a public location, which arrangement allows dial pulses for a dialed number to be generated by the phone only if the number is preceded by a dialed 0.
In certain locations such as resort areas or institutions, the demand for public telephone service is high. This demand is typically handled by coin telephones and coin class central office facilities; however, the use of such facilities has presented several difficulties. First, in some areas, particularly in large schools or prisons, it is not possible to provide sufficient coin equipment to handle the demand. Secondly, in other areas, particularly resort areas, customers frequently do not have the coins which are necessary to initiate coin calls. If these customers were allowed to contact an operator without depositing coins and without using coin class central office equipment, the call could be billed through a collect, credit card, or third-party billing arrangement.
Therefore, it is desirable to permit customers to initiate public telephone service from an ordinary telephone station and associated line, thereby dispensing with the need for coin class equipment. Of course, to prevent customer misuse, a restriction arrangement must be provided. It is particularly advantageous to direct all calls to an operator position so that customers who do not have coins are able to initiate an operator-handled call.
Finally, it is desirable that the customer be allowed to dial an entire number (preceded by a 0 to route the call to an operator). With this arrangement, efficient use may be made of automated operator systems now available in many areas which systems can forward the called number to the operator. The called number provides the automatic equipment with the necessary charging and routing information so that the call may be handled rapidly after the operator is advised by the calling party how the call is to be billed.
Arrangements which allow the customer to dial an operator-handled call from a public telephone without depositing coins have been utilized in the prior art. However, existing designs typically require special dial tone-first circuitry, and/or external power supply arrangements at the station set location, and special central office switching equipment. Such public telephone arrangements customarily necessitated the use of the well-known coin telephone sets and special coin classes of service to enable an operator appropriately to recognize and be informed of the charge service required on a call.
Accordingly, it is an object of the present invention to provide a noncoin rotary dial set which may be placed in a public location to allow a customer to dial an operator-handled call without depositing coins.
It is a further object of the present invention to restrict outgoing calls from a noncoin rotary dial set without requiring extensive circuitry modifications or external power supply arrangements.